Method of making electrotypes



Patented Aug. 25, 1942 METHOD OF MAKING ELECTROTYPES Eignar Ringquist, Worcester, Mass.

No Drawing. Application April 21, 1941, Serial No. 389,623

2 Claims.

This invention relates to improvements in the combining of metals and is directed more particularly to the provision of a novel method of combining metals and means for facilitating the carrying out of that method.

It is one of the principal objects of the inven tion to provide a new method and means of combining such metals as lead and copper and the invention therefore is particularly applicable to the manufacture of electrotypes. As will appear, the practice of the method of this invention renders the production of electrotypes much cheaper, easier, and quicker than is now possible.

According to present practice, a copper electroplating shell is deposited on the lead by a long series of involved steps requiring considerable effort and time. Usually the shell is first dipped in sulphuric acid, for purposes of cleaning, etc., and then the acid must be Washed off.

Then the back of the copper shell, that is the side that is to be nearest the lead, is painted or coated in some manner with zinc chloride. Over this coating is applied a relatively thin layer of tinfoil and then the shell is washed again.

The sequence of these steps may vary but, in any event, it will be seen they are numerous and require time and expense. After the preparation such as has just been described, the molten lead may be poured in or on the back of the shell.

It has always been thought that the two metals, which We particularly desire to combine, namely copper and lead, cannot be made to adhere with any degree of satisfaction unless substantially the above-described process is carried out. As is obvious, unless the metals are firmly stuck together, the electrotype is of little value.

According to this invention, I have conceived a new method which is much less expensive than the prior practice and which includes much fewer steps so that it may be carried out more handily and in much less time. At the same time, there is no loss in efliciency as far as the combined metal product is concerned.

First, I heat the copper shell to a temperature which is 700 F. Then, there is applied to the back of the shell a certain fluid composition, which will presently be described, and this composition may be applied to the shell in any one of various Ways, such as by spraying, brushing or the like.

The shell is then ready to have molten lead poured into or onto its composition-bearing side. This may be done at any time and results in a composite product wherein the two metals are firmly combined.

It will be seen that but a relatively few steps and but a short time are required. That is to say, the various dipping, washing, and coating steps of the prior practice are for the most part eliminated.

The preferred fluid composition which I employ, and what may be termed the fixing agent, consists of a solution of stannous chloride and hydrochloric acid. In practice, it has been found desirable to place a certain amount of the acid in water and then add stannous chloride crystals, but it is to be understood that the stannous chloride may be added to the water before the acid, if desired.

Best results have been obtained where fullstrength hydrochloric acid is used and the preferred proportions are about five ounces of the acid to one gallon of water. To this mixture may be added from six to seven and one-half ounces of stannous chloride and a satisfactory amount is usually about siX and three-quarter ounces.

The fluid composition is applied to the shell shortly after it has been heated as mentioned, or at least while it is still in a heated state. The fluid will tend to turn to a brown color after its application to the warm copper and When it has done so, the molten lead may then be poured in.

.The result is an economically-made and efiiciently-operative electrotype where the parts are as firmly united as desired. The number of steps involved is much less than that of the prior processes and both labor and materials are saved.

The invention may be embodied in other specific forms without departing from the essential characteristics thereof. Hence, the present embodiments are therefore to be considered in all respects merely as being illustrative and not as being restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all modifications and variations as fall within the meaning and purview and range of equivalency of the appended claims are therefore intended to be embraced therein.

What it is desired to claim and secure by Letters Patent of the United States is:

l. The method of making an electrotype including a copper shell and lead backing united thereto which consists in, heating a copper shell, applying to the rear side thereof a fixer including stannous chloride and hydrochloric acid whereby it is dried by the heated shell, and when the fixer is dry pouring molten lead onto the fixer and allowing it to cool and harden thereby providing a rigid metal backing united to the shell.

2. The method of making an electrotype including a copper shell and lead backing united thereto which consists in, heating a copper shell, applying to the rear side thereof a fixer including stannous chloride and hydrochloric acid whereby it is dried by the heated shell, and when the fixer is dry pouring molten lea-d onto the fixer and allowing it to cool and harden thereby providing a rigid metal backing united to the shell, the temperature to which the shell is heated being in the neighborhood of 700 F. and the proportions of stannous chloride and hydrochloric acid to a gallon of water being 6 to 7 /2 ounces and approximately 5 ounces respectively.

EIGNAR RINGQUIST. 

